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矩形矿井巷道内UWB路径损耗研究
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作者 韩梦辉 曹波 +2 位作者 王世博 张华 朱万洁 《煤炭技术》 CAS 2024年第10期218-222,共5页
为了探究UWB无线信号在煤矿巷道内的传输特性,结合电磁波信号的传输以及反射定律原理,分析了矩形矿井巷道中可能出现的不规则传输路径其过程中存在的粉尘浓度、空气湿度、四壁不同程度的粗糙面以及煤壁倾斜程度等因素引起的信号损耗。... 为了探究UWB无线信号在煤矿巷道内的传输特性,结合电磁波信号的传输以及反射定律原理,分析了矩形矿井巷道中可能出现的不规则传输路径其过程中存在的粉尘浓度、空气湿度、四壁不同程度的粗糙面以及煤壁倾斜程度等因素引起的信号损耗。构建了不同条件下的损耗模型,并运用MATLAB软件对巷道内信号的损耗进行了仿真分析。仿真结果表明:粉尘浓度和空气湿度都会对电磁波造成衰减,增加粉尘浓度加速信号的损耗,其信号的衰减要远大于空气湿度引起的损耗;粗糙和倾斜加速了信号的衰减,但是粗糙和反射引起的损耗远远低于倾斜引起的损耗,倾斜损耗起主导作用。 展开更多
关键词 UWB信号 粉尘浓度 空气湿度 倾斜损耗 粗糙损耗
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Influence of Blade Chordwise Lean on Development of Cascade Losses
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作者 HanWanjin HuangHongyan 《Journal of Thermal Science》 SCIE EI CAS CSCD 1996年第4期224-230,共7页
An experimental investigation was carried out on the effect of blade chordwise lean on the losses in highly loaded rectangular turbine cascades. Detailed measurements include 10 traverses from upstream to downstream o... An experimental investigation was carried out on the effect of blade chordwise lean on the losses in highly loaded rectangular turbine cascades. Detailed measurements include 10 traverses from upstream to downstream of the cascades with five-hole spherical probes. Compared with the experimental data of the conventional straight and pitchwise lean blades under the same conditions, it is shown that the effect of chordwise lean on the development of the cascade losses is similar to that of pitchwise lean. However, the chordwise lean produces smaller streamwise adverse pressure gradients near both endwalls and a smaller spanwise negative one starting from the acute angle side in the first part of the passages in chordwise lean cascade, thereby the saddle point separations and intensities of the passage vortices are weakened and the secondary vortex losses are cut down notably. 展开更多
关键词 blade chordwise lean cascade losses vortices.
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